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Table of contents
1.
Introduction
2.
What is Swapping in Operating Systems (OS)?
3.
Example
4.
Need of Swapping in Operating System
5.
Advantages of Swapping in OS
6.
Disadvantages of Swapping in OS
7.
Working of Swapping technique in Operating System
7.1.
Selection 
7.2.
Data Transfer
7.3.
Process Suspension 
7.4.
Loading
7.5.
Resumption 
8.
Frequently Asked Questions
8.1.
What is swapping in operating system? 
8.2.
What is swapping in programming? 
8.3.
What is swap space operating system? 
8.4.
Why use swapping in OS? 
8.5.
Why is swap memory used?
9.
Conclusion
Last Updated: Mar 27, 2024
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Swapping in Operating System (OS)

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Speaker
Anubhav Sinha
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25 Jun, 2024 @ 01:30 PM

Introduction

Swapping is a technique used by operating systems to move less frequently used memory pages from RAM to a hard disk.

An operating system (OS) is a software program that serves as a conduit between computer hardware and the user. It is a piece of software that coordinates the execution of application programs, software resources, and computer hardware. 

It also aids in the control of software and hardware resources such as file management, memory management, input/output, and a variety of peripheral devices such as a disc drive, printers, and so on. To run other applications, every computer system must have at least one operating system. 

In this article, we are going to discuss Swapping in OS in detail.

swapping in operating system

What is Swapping in Operating Systems (OS)?

Swapping in OS is a memory management technique that temporarily swaps processes from main memory to secondary memory or vice versa which helps to increase the degree of multi-programming and increase main memory utilisation.

There are two steps in the process of Swapping in the operating system:

  1. Swap In: Swap-in is the process of bringing a process from secondary storage/hard disc to main memory (RAM).
  2. Swap Out: Swap-out takes the process out of the Main memory and puts it in the secondary storage.
Swapping in Operating Systems (OS)

In the above diagram, process P1 is swap out so the process with more memory requirement or higher priority will be executed to increase the overall efficiency of the operating system. While the process P2 is swap in for its execution from the secondary memory to the main memory(RAM).

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Example

Let's understand this with the help of an example. The process size of the user's process is 4096KB, and the transfer rate is 1 Mbps. Now we'll find out how long it will take to move from main memory to secondary memory.

 

User process size = 4096KB 

Data transfer Rate = 1024 Kbps

Time = User process size / Data transfer Rate

4096 / 1024 = 4 seconds 

4000 milliseconds

The process will now take 4000 milliseconds.

 

You can also read, Components of Operating System

Need of Swapping in Operating System

TSwapping is also known as paging. The need for swapping arises when the overall efficiency of the operating system decreases. It is due to the amount of memory required by executing processes exceeding the available RAM space. It is a technique used by the operating system to manage the memory of the system. Swapping moves less frequently used memory pages from RAM to a hard disk. This process of the swap makes space for more frequently used programs or data.

Swapping can be used to preempt the inactive or idle process to free up the memory. In this way, swapping increases the efficiency and degree of multi-programming in the operating system.

We can conclude that swapping plays a vital role in managing resources and thus ensuring efficient use of memory in the operating systems.

Advantages of Swapping in OS

  • Swapping processes improve the degree of multi-programming.
  • It provides the advantages of Virtual Memory for the user.
  • Swapping reduces the average waiting time for the process because it allows multiple processes to execute simultaneously.
  • It helps in better memory management and efficient utilization of RAM.

Disadvantages of Swapping in OS

  • The swapping algorithm must be perfect; otherwise, the number of Page Faults will increase, and performance will decrease.
  • Inefficiency will occur when there are common/shared resources between many processes.
  • The user will lose information if there is heavy swapping and the computer loses its power.

Working of Swapping technique in Operating System

Swapping is a memory management technique employed by the operating system to efficiently utilize the limited physical memory (RAM) available in a computer system. When the system's RAM becomes overloaded due to running multiple processes simultaneously, some parts of a process or an entire process might be temporarily moved to secondary storage (usually the hard disk) to free up space for other processes.

The process of swapping involves the following steps:

Selection 

The operating system selects a process that needs to be swapped out of the main memory. This selection is often based on priority, execution time, or other criteria.

Data Transfer

The data of the selected process, including its code and data, is transferred from the RAM to a designated area on the disk known as the swap space.

Process Suspension 

The selected process is suspended, and its state, including register contents and program counter, is stored in memory.

Loading

If another process needs to be brought into memory for execution, the operating system selects a process from the disk's swap space, loads it into the RAM, and restores its saved state.

Resumption 

The resumed process continues its execution from where it was suspended, typically unaware of being temporarily swapped out.

Swapping helps manage the memory demands of various processes efficiently, allowing more processes to run than the physical RAM can accommodate. However, swapping can introduce delays due to the time needed to move data between main memory and the disk. To minimize this performance impact, modern operating systems use sophisticated algorithms to decide which processes to swap and when, aiming to optimize overall system performance while ensuring smooth multitasking.

Frequently Asked Questions

What is swapping in operating system? 

Swapping in an operating system involves moving data between RAM and disk to manage memory efficiently, temporarily transferring inactive memory pages to disk to free up RAM for active processes, thereby preventing system slowdowns and crashes due to insufficient memory. 

What is swapping in programming? 

In programming, swapping typically refers to exchanging the values of two variables, allowing for manipulation and rearrangement of data within a program's memory space, facilitating various algorithms and operations. 

What is swap space operating system? 

Swap space in an operating system is a designated area on disk used to temporarily store inactive memory pages when RAM is full, enabling the system to maintain performance by swapping out less frequently accessed data while keeping frequently used data in RAM. 

Why use swapping in OS? 

Swapping in OS is utilized to optimize memory usage, ensuring that active processes have access to sufficient RAM by temporarily transferring less frequently used data to disk, thereby preventing memory exhaustion and improving overall system responsiveness and stability. 

Why is swap memory used?

Swap memory is employed in operating systems to provide additional virtual memory when physical RAM is insufficient, helping to prevent system crashes and slowdowns by extending the available memory capacity and accommodating the needs of running processes beyond the limitations of physical memory.

Conclusion

In conclusion, swapping in operating systems is a vital mechanism for managing memory efficiently. By temporarily transferring inactive data between RAM and disk, swapping optimizes memory usage, prevents system slowdowns, and maintains overall stability and responsiveness, ensuring that active processes have access to sufficient resources for smooth operation.

Recommended Readings:


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